https://www.polygon.com/2018/6/21/17479842/pokemon-go-legendary-raid-battle-regice

Although overshadowed by this week’s trading feature update, a new legendary Pokémon has arrived in Pokémon Go. The ice-type Regice, one of the more difficult Pokémon to obtain in the mainline games, will take part in Raid battles from now through July 19.

Niantic has yet to formally reveal Regice’s introduction, although push notifications and a livestream teardown confirm that the Pokémon is coming at some point today. It’s the latest and one of the last third-generation legendaries to join Pokémon Go, with its companions — Registeel and Regirock — still to be discovered.